1. Field of the Invention
The present invention relates generally to a gyro apparatus and, in particular, is directed to a vibration or tuning fork type gyro apparatus.
2. Description of the Prior Art
As a vibration type gyro apparatus of this kind, there has been so far proposed one such as, shown in FIG. 1. In the prior art gyro apparatus as shown in FIG. 1, a tuning fork 1 is attached to a base table 2 with a flexible shaft 3. A displacement detector 6 and drive coils 4 are provided in association with the tuning fork 1 at a position near the upper end thereof and the output from the displacement detector 6 is supplied through a drive amplifier 5 to the drive coils 4 to thereby maintain the amplitude of the vibration of the tuning fork 1 constant. When an angular velocity .OMEGA. is applied around a (Z--Z) axis of the flexible shaft 3 of the tuning fork 1, there is produced Coriolis force F.sub.c which corresponds to a vibration velocity v of the tuning fork 1 and the input angular velocity .OMEGA., which causes the tuning fork 1 to be alternately rotated around the (Z--Z) axis and, or a twist vibration is generated in the tuning fork 1.
In the prior art example of the gyro apparatus shown in FIG. 1, the twist vibration of the tuning fork 1 is detected by a twist detector 8 and the detected output from the twist detector 8 and the output from the drive amplifier 5 are synchronously rectified by a demodulator 7 to thereby detect the input angular velocity .OMEGA.. Thus, a gyro apparatus is constructed.
However, in the prior art vibration type gyro apparatus, since the heavy tuning fork 1 is supported in a cantilever fashion, the load capacity of the flexible shaft 3 must be large. When this support portion must be large, since the above-mentioned prior art vibration type gyro apparatus is formed such that the Coriolis force F.sub.c corresponding to the input angular velocity .OMEGA. is derived as the rotation angle of the tuning fork 1 which has a large moment of inertia, the prior art gyro apparatus has poor sensitivity for the input angular velocity .OMEGA.. To increase this sensitivity, the entire apparatus must be made large. Further, since the flexible shaft 3 and the twist detector 8 are respectively formed of different members, the construction of the gyro apparatus is very complicated and the detection sensitivity is quite low.